I ended up going with the Nemo Excel myself. After reading an number of reviews on both, they both seemed pretty comparable. Ultimately price was the deciding factor, new to dive and spending lots of $$$ right now. I got the Nemo about $100 cheaper than the cheapest price I saw for the D4.
The Nemo is a nice watch, but I don't like not having the SI feature which from what I've read is pretty standard on most watches. From what I've read it may be a bit more challenging downloading the dive log via infrared as opposed to the direct connection which I believe the D4 has. It feel's like a pretty solid/durable watch though. However, still completing my OW and having only used it for my first two ocean dives, I'm not necessarily qualified either way to say how good/bad it is. I will say that my rental gear had a computer on the gauges (Suunto, but don't remember which one) and it matched up exactly for depth, but the Nemo was 2-4 degrees warmer for temp (perhaps body heat from being on wrist?). One thing I did like was the safety stop feature that showed min/sec and as I went down too far or up too far I could watch the seconds increment or decrease. On the Suunto gauge it only displayed the minutes.